Electrical switch



MaFch 1951 A. WISBEcKER 2,545,284

ELECTRICAL SWITCH Filed Sept. 7, 1948 2 Sheets-Sheet l A? TURE ARMATURE /6 ELECTROMAGNET March 27, 1 51 A. L. WEISBECKER ELECTRICAL SWITCH 2 Sheets-Sheet 2 Filed Sept. 7, 1948 Augasi L. Wzlsbecizfer Patented Mar. 27, 1951 UNITED STATES PATENT OFFICE ELECTRICAL SWITCH August L. Weisbecker, Williamstown, N. J.

Application September '7, 1948, Serial No. 48,069

12 Claims. 1

This invention relates to switching devices and mcre particularly to such a device having a high rate of switching of the order of 100 cycles per second combined with a very short switching interval of the order of a few microseconds.

SQ-Qalled electronic switches are known, by means of which two voltages may be simultaneously viewed on a cathode-ray oscillograph. However, such apparatus is both bulky and expensive. It is also subject to the limitation that high switching rates, combined with a short switching interval cannot be maintained without considerable distortion of the applied voltages. It is accordingly an object of my invention to provide an electrically operated switch peculiarly adaptable to such usage, which will overcome these limitations. While my invention is designed primarily for use in the apparatus disclosed in my copending application Serial No. 37,880, filed July 9, 1948, it will be apparent that it is not limited to such use. In fact, it has broad application throughout the electrical industry wherein high switching rates with very short switching intervals are required. It can be used, for example, in place of vibratin reed devices now used in mobile radio power supplies.

Briefly, the apparatus of my invention comprises a torsional spring element, supported at each end, operated in oscillatory motion by suitable actuating means, and having a switch operating lever connected thereto. The switch itself, for example, may be of the knife blade type inv which case the switch operating lever strikes a hammer-like blow against alternate sides of the knife blade.

The accompanying drawings show a preferred embodiment of my invention in which:

Figure 1 is a side elevation.

Figure 2 is a top view.

Figure 3 is a side elevation from the opposite side of that shown in Figure 1.

Figure 4 is a chopped explodedperspective view of the torsional element.

Figure 5 is a sectional view taken on line 5'5 oi -fi ure 1.

Figure 6"is an enlarged view partially in section of Figure 1.,

Figure '7 is an exploded perspective of the frame and stress producing elements.

Eigure 8 is an enlarged perspective view of theswitch contacts and mounting block.

Figure 9 is an enlarged perspective view of the switc it el The torsionalspring element I0, as shown, is made up. of ap ir' of members I'I andv I2 substantially V-shaped in cross section and supported in back to back relationship. This is best shown in Figure 4. These members are preferably made of the alloy known commerically as Nichrome V, but it is to be understood that other alloys having adequate fatigue loading resistance could also be used. The members I I and I2 are held in back to back relationship by having their ends secured in the two end blocks I3 and I4. It will be apparent that there are other possible mechanical equivalents of this construction. The members I5 and it (best shown in Figure 5) secured to the element It are made of magnetic material, and serve a double purpose. First they add mass to the oscillating system, and by reason of the tie member i1 and the rigid supports at each end of the spring, the entire system tends to have but one natural mode of oscillation. Second, they provide a magnetic portion for the system so that it may be driven electromagnetically a the armature of a motor. The symmetrical arrangement of the radially extending arms of members I5 and I6 is more important than the number of arms. The electromagnet I8 is centrally mounted between corresponding arms of magnetic members I5 and I6, as shown, so that when energized, a substantially equal force will be exerted on I5 and I6, and the torsional spring element will be deflected accordingly. The force exerted on the radiallyextending arm of members I5 and I6 i due to the fact that a magnetic material will always tend to move. toward the region of maximum flux density of the magnetic field to which it is subjected. As best shown in Figure 5, the armsof members i5 and I6, when in their'normal or restposition, lie outside the field of maximum flux produced'when electromagnet I8 is energized. The circuit of electromagnet H3- includes 2; normally closed circuit breaker Iii-comprising afixed contact 20 and movable contact 21-, the latter being mounted on arm 22; The arm 22' is rigidly secured to the torsional spring element I0. When. electromagnet I8 is energized, the magnetic force exerted on members i5 and I6 twists the torsionalspring element and contact is then broken between 20a'nd 2|. The torsional element It] then returns toward its position of rest and contact is again made at 2B and 2| so that the cycle is continuous, once started It should'b'e apparent, however, that means other than the electromagnetic means shown here could be used to apply a regularly recurrent force-to the torsional sprin element I to cause it to oscillate about" its longitudinal axis: Ari

- 3 electric motor, for example, with a cam on its shaft could be arranged to accomplish the same result.

In order to vary the frequency of oscillation of the torsional spring element IE3, it is convenient to employ means to set up a longitudinal stress in this element. In the drawings, therefore, I show a preferred means for accomplishing this. As shown in Figures 1, 3, and 6, one end of the spring element It! is rigidly connected to a rigid end plate 23 of the frame 2d. At the opposite end, a resilient end plate member 25 supports the spring element. Spacer members 26 separate, in fixed relation, a second resilient plate 27 from plate 25 and a rigid end plate 28. Rigidly secured to plate 21 is a threaded member, e. g. machine screw 29, which protrudes through the rigid end plate 28. bias screw 29 against the end of torsional spring element ill through helical spring 33. A hollow shaft 3i is threaded to mate with screw 29. A handle 32 secured to shaft 3! provides means for varying the longitudinal stress on the torsional spring it. The small helical spring 33 serves to act as a cushion and to force transmitting element between the end of torsional spring l9 and machine screw 29.

The apparatus thus far described is for the purpose of operating the switch 3? in a manner characterized by high switching rates of the order of 100 cycles per second and short switching in tervals of the order of a few microseconds. A preferred construction of the switch 34 is shown in Figure 9, and consists first of a pair of fixed leaf spring contact members 35 and 36. These are mounted in a laminated insulating block 31. The arm 38 of the switch is frictionally held and pivotally mounted between two other leaf spring members 39 and 40. A switch operating lever 4| is rigidly connected to the torsional spring element ill, at about its mid point. At the outer extremity of lever N, there is an opening which surrounds the outer end of the switch arm 38. Some clearance is desired between these two members so that arm 36 when struck by the lever M will remain in contact with either 35 or 36 until struck in the opposite direction. Contacts 35 and 36 are similar in all respects and are made of leaf spring material. As shown in Figure 8, their ends are bent to form tubular portions thereon. These are so designed that the point at which arm 38 strikes them is a node point for their natural mechanical vibrations. This feature minimizes contact chatter when the switch is in operation.

From the foregoing, the operation of my device will be clear. The oscillatory motion of the torsional spring element ill, causes the lever M to strike repeated hammer-like blows against alternate sides of the switch arm 38. Because of the clearance or lost motion connection between these two members, and the frictional loading on arm 38, the latter will strike and remain in contact with either 35 or 36 until struck from the opposite side. This results in a substantially equal duration of contact of arm 3% alternately with the switch contacts 35 and 36 throughout the cycle of operation. It also results in an extremely short switching interval between contact points. Thus if a source of voltage is connected to 35 and another to 35, these voltages may be connected alternately to other circuits such, for example, indicating circuits or measuring instruments which are connected to the switch arm 38.

A leaf spring 30 serves to The following claims set forth with particu larity the novelty of my invention. What I claim is:

l. A switching device for operation at switching rates of the order of cycles per second and switching intervals of a few microseconds comprising: an elongated torsional spring element; means for rigidly supporting said element at its opposite ends to allow torsional deflection of the intermediate portion thereof; means to apply a recurrent torsional stress to said element to produce oscillatory motion about its 1ongitudinal axis; an electric switch including a movable switch arm mounted adjacent said element; and lever means, one end of which is attached to said spring element and the other end of which is operatively connected by means of a lost motion connection to said switch arm, whereby said switch is operated by said lever means striking hammer blows on alternate sides of said switch arm as said spring element is oscillated.

2. A switching device, for operation at switch ing rates of the order of 100 cycles per second and switching intervals of the order of a few microseconds, comprising: a torsionally-resilient transversely stiff elongated spring element; means for rigidly supporting said element at its opposite ends to allow torsional deflection of the intermediate portion thereof; means to apply a recurrent torsional stress to said element to produce oscillatory motion about its longitudinal axis; an electric switch including a movable switch arm mounted adjacent said elongated element; a switch operating lever rigidly connected to and extending radially from said elongated element; and means at the outer end of said lever forming an operative, lost motion connection with said switch arm, whereby said switch is operated by said lever means striking hammer blows on alternate sides of said switch arm as said springelement is oscillated.

3. A switching device, for operation at switching rates of the order of 100 cycles per second and switching intervals of the order of a few microseconds, comprising: a torsionally-resilient transversely stiff elongated spring element; means for rigidly supporting said element at its opposite ends to allow torsional deflection of the intermediate portion thereof; electromagnetic actuating means to apply a recurrent torsional stress to said element to produce oscillatory motion of said element about its longitudinal axis; an electric switch mounted adjacent said element and having at least one fixed contact and a switch arm movable into and out of engagement therewith; a switch operating lever rigidly connected to and extending radially from the midsection of said element; and means at the outer end of said lever forming an operative lost, motion connection with said switch arm, whereby said switch is operated by said lever means striking hammer blows on alternate sides of said switch arm as said spring element is oscillated.

4. A switching device, for operation at switching rates of the order of 100 cycles per second and switching intervals of the order of a few microseconds, comprising: a torsionally-resilient transversely stiff elongated spring element; means for rigidly supporting said element at its opposite ends to allow torsional deflection of the intermediate portion thereof; means to apply a recurrent torsional stress to said element to cause oscillatory motion about the longitudinal axis thereof said means including an electromagnet and a circuit breaker therefor carried by said Summer elongated member; an electric switch having at least two relatively fixed contacts and a switch arm movable therebetween, mounted adjacent said element; a switch operating lever rigidly connected to .and extending radially from the m'idsection of said member; and means at the outer end of said lever forming an operative lost motion connection with said switch arm to provide a lost motion .connection between said lever and .said arm whereby said switch is operated .by saidlever zmeans striking hammer blows -.on alternate sides of said switch arm as said spring element is oscillated.

5. In a device as defined by claim 2, in which the elongated member comprises: a pair of members substantially V-shaped in cross section; a pair of end blocks; said members being connected at each end thereof to said end blocks to pro-- vide an elongated member substantially X-shaped in cross section and having a high degree of transverse rigidity combined with a high degree of torsional resilience.

6. A switching device, for operation at switching rates of the order of 100 cycles per second comprising: a torsionally-resilient transverselystiff torsional spring element; means providing a support and preventing rotative movement of said element at each end thereof; an electric switch including a movable switch arm mounted adjacent said element; a switch operating lever rigidly connected to and extending radially from the approximate center of said element; means providing a lost motion connection between said lever and said switch arm; a pair of weights rigidly connected to the torsional element at points substantially equidistant from the ends and center thereof, said weights comprising a plurality of symmetrical radially extending arms of magnetic material; a longitudinally extending bar member joining corresponding arms of said weights; an electromagnet mounted adjacent said spring and having its pole faces disposed in close proximity to corresponding arms of said magnetic members; a normally closed electric circuit breaker in series with said electromagnet; a circuit breaker arm rigidly connected to and extending radially from said element; and means for energizing said magnet to cause said weights to move in a circular path toward the center of the pole faces of said electromagnet and against the resistance to torsional movement of said element, whereby the said circuit breaker is rendered operative and the cycle repeated to produce oscillatory motion of said element that is efiective to operate the said switch at a rate corresponding to the oscillation frequency of the said element.

7. A device as defined by claim 6 in which means are provided to place said spring element under a variable longitudinal stress to vary the period of oscillation of said spring element.

8. A device as defined by claim 1 in which the said torsional element is mounted in a frame; means for rigidly connecting one end of said element to one end of said frame; a resilient plate member connected to the other end of said frame; means for supporting the other end of said element in said resilient plate member; threaded adjustment means mounted on said frame; means providing a connection between said adjustment means and said element whereby the longitudinal stress in said element may be varied in order to change the natural frequency of oscillation of said element.

9. In a device as defined by claim 6 in which thesai'd electric switch, comprises: a :pair of fixed leaf spring contacts mounted adjacenteach other in an insulating block, said .contacts having their free ends bent to form tubular contact portions thereon; a knife blade switching arm, pivotally mounted, and extending between said contacts; means for frictionally loading said switch arm; the tubular portions of said contacts being so located with respect to said switch arm that contact 'th-erebetween occurs at a point which is a node for the natural mechanical resonance vibration of said contacts.

10. A switching device, characterized by operation at switching rates of the order of cycles per second and switching intervals of the order of a few micro-seconds, comprising: a torsionally-resilient transversely-still elongated torsional spring element; means providing a upport and preventing rotative movement of said element at each end thereof; a pair of magnetic members rigidly connected to said spring element at points substantially equidistant from the ends and center thereof, said members having a plurality of symmetrical radially extending arms; a longitudinally extending strip connecting corresponding arms of said members at the outer extremities thereof; an electromagnet mounted adjacent said element and centrally disposed between said magnetic members, the pole ends of said electromagnet being supported in close proximity to a corresponding pair of said arms; a normally closed circuit breaker in series with said electromagnet; a circuit breaker arm rigidly connected to and extending radially from said element; an electric switch including a movable switch arm mounted adjacent said element; a switch operating lever also rigidly connected to and extending radially from the mid-section of said element and having an opening in the outer end thereof surrounding said switching arm, whereby a lost motion connection is provided between said lever and said switching arm; a source of electrical energy for said electromagnet; and a threaded type loading means for varying the longitudinal stress in said torsional element to change the natural period of oscillation thereof, thereby changing the switching rate.

11. A switching device for operation at switching rates of the order of 100 cycles per second and switching intervals of a few micro-seconds comprising: a pair of elongated members substantially v-shaped in cross-section, connected at their ends in back-to-back relationship to form a spring member substantially X-shaped in connection; means for supporting said spring member at its opposite ends to permit torsional deflection of the intermediate portion about the longitudinal axis thereof, at least one support bein rigid; means to apply a recurrent torsional stress to said spring member to produce oscillatory motion about its longitudinal axis; an electric switch including a movable switch arm mounted adjacent said spring member; and lever means one end of which is attached to said spring member and the other end of which is operatively connected by means of a lost motion connection to said switch arm, whereby said switch is operated by said lever means striking hammer blows on alternate sides of said switch arm as said spring member is oscillated.

12. In a device as defined by claim 11, a resilient support for one end of said spring member; .and threaded adjustment means connected to the resiliently supported end of said spring member to set up and vary the longitudinal stress therein tr) change the natural period of oscillation of said element.

AUGUST L. WEISBECKER.

REFERENCES CITED UNITED STATES PATENTS Number Name Date Seeley Oct. 24, 1905 Number 1,639,178 1,750,275 1,920,135 1,932,164 2,043,152 2,183,934 2,313,919 2,349,929 2,445,401 2,499,632

- Name Date Guillet Aug. 16, 192'? Legg Mar. 11, 1930 Allen July 25, 1933 Petit Oct. 24,1933 Cook June 26, 1936 Heiland Dec. 19, 1939 Burt Mar. 16, 1943 Atkins May 30,1944 Langer July 20, 1948 Coake Mar. 7, 1950 

